This invention relates to a lubricant used for forging a steel material, and particularly to a particulate lubricant to be sprayed on the surface of the steel material to form a lubricant coat thereon.
This invention also relates to a method for forming a lubricant coat on the surface of a linear material, for example, a wire rod.
Recently, automobile, electronic, electric, architectural and other industrial fields have increasingly required the reduction in the manufacturing cost of various parts. Consequently, the development of cold forging and warm or hot forging operations are increasingly demanded. Most parts are made of carbon steel and low alloy steel through cold forging. For the cold forging, a horizontal parts former, a vertical parts former, a vertical press and other devices are available. The vertical press incorporates structure for the dropping of mineral oil or emulsive lubricant onto the surface of a starting material. The starting material is thus prevented from being burnt in a metal mold during forging.
When small screws and other small parts are forged, after a linear material is cut into desired dimensions, forging is carried out. Usually, an oxalate coat is formed on the surface of the linear material to be forged. The oxalate coat lubricates the surface of the linear material and prevents the linear material from being burnt in a metal mold. According to the type of the parts to be forged, in addition to the oxalate coat, lubricating oil is dropped onto the surface of the linear material to enhance the lubricating performance.
When the lubricating oil is dropped, the lubricating oil is scattered around, thereby deteriorating the environment. Since the lubricating oil lacks in heat resistance, the lubricating oil is also inappropriate for hot forging. Further, the lubricating oil provides insufficient lubricating performance, and is also inappropriate for hard to work materials.
To form the oxalate coat on the surface of the linear material, linear material in the form of a coil is soaked in a solution tank containing oxalate solution. The surface of the linear material in the solution tank, however, has some portions to which the oxalate solution is hard to adhere, irrespective of a lubricant coat forming method, for example, through the chemical reaction or just the application of the oxalate solution. Even when a more effective lubricant solution is developed to form a lubricant coat appropriate for forging hard to work materials, forging steps need to be complicatedly combined with the steps for forming a lubricant coat. Furthermore, the soaking of the linear material in the solution tank increases manufacturing cost.
To solve these problems, a method for forming a uniformly thick and effective lubricant coat has been developed. As a result, a method for forming the lubricant coat by electrostatically spraying a particulate lubricant is proposed. A lubricant used for forming a lubricant coat on the surface of hard to work materials, however, has not been developed.